A virtual disk may be stored on a disk volume that has been thin-provisioned. A thin-provisioned volume has a physical capacity and a virtual capacity, the virtual capacity being larger than the physical capacity, and provides a space efficient way of storing data. A thin-provisioned volume may, in particular, be used to store in a compact form a copy of a base volume that contains the base state of a virtual machine. After the copy has been created, data on the thin-provisioned volume may subsequently be modified and additional new data may be written to the volume causing it to become inconsistent with the original virtual machine base state.